When a current electronic cigarette simulates a smoking process, an electrical heating wire generates heat and produces smoke, and inhaled air flows takes the smoke out though a cigarette holder. A sealing ring is mounted under the cigarette holder to avoid tar leakage via joints of the cigarette holder and a protecting jacket. In the prior art, one kind of sealing ring is in tight contact with an outer wall of a breather pipe, and another kind of sealing ring is integrated with the breather pipe, particularly, the sealing ring extends axially to form the breather pipe. However, such structures and assembly methods of sealing rings are unable to avoid tar condensation inside the cigarette holder, which makes the condensed tar inside the cigarette tar may often be sucked into mouths of smokers.